<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script>
<![CDATA[

function boom()
{
  document.getElementById("i").selectionEnd;
  document.getElementById("a").appendChild(document.getElementById("b"));
}

]]>
</script>
</head>
<body onload="boom();">

<mrow xmlns="http://www.w3.org/1998/Math/MathML" id="a"><mrow id="b"/><input xmlns="http://www.w3.org/1999/xhtml" id="i" /></mrow>

</body>
</html>
